INTRODUCTION
Land degradation in the form of soil erosion, deforestation, overgrazing, salinization and alkalization contributes significantly to low agricultural productivity. This causes food insecurity and poverty in many developing countries of the world including Ethiopia (Pagiola, 1999; Shiferaw et al., 2007). Land degradation was a significant global issue during the 20th century and remains of high importance in the 21st century as it affects the environment, agronomic productivity, food security and quality of life (Eswaran et al., 2001). For developing nations, soil erosion is among the most chronic environmental and economic burden (Taffa, 2002). In Ethiopia agriculture forms the dominant sector of the economy which provides about 52% of the country’s gross domestic product (GDP), over 80% of its employment, and 90% of its export earnings (World Bank,2000). The rates of soil erosion in Ethiopia are frighteningly high. Serious erosion is estimated to have affected 25% of the highland area. Close to 4% of the highlands are now so seriously eroded that they will not be economically productive again in the foreseeable future (Teklu and Gezahegn, 2003). The causes of land degradation include such factors as population pressure on resources; poverty; high costs or limited access of farmers to fertilizers, fuel and animal feed; insecure land tenure; limited farmer knowledge of improved integrated soil and water management measures; and limited or lack of access to credit.
(Gebremedhin, 2004; Takie, 1999; FAO, 1985). The dissected terrain with steeper slope gradients and the high intensity of rainfall lead to accelerated soil erosion once deforestation occurs (Badege, 2001). With high intensity rainstorms and extensive steep slopes, steep lands in particular suffer from high rates of soil erosion and nutrient loss. Although, data on the extent of the problem are patchy and inconsistent, available estimates indicate that soil erosion averages nearly 10 times the rate of soil regeneration in the highlands, and the rate of soil nutrient depletion is the highest in sub-Saharan Africa (FAO, 1993; Hurni, 1988, 1993; Stoorvogel et al., 1993). Soil erosion is severe on cultivated lands, where the average annual loss is 42 tons/ha, compared with five tons/ha from pastures (Hurni, 1993). In order to protect soil resources from erosion, considerable efforts should be made to ensure the life continuity in the future. Achieving sustainable pathways out of the downward spiral of land degradation and poverty requires that farmers adopt profitable and sustainable land management practices, or pursue alternative livelihood strategies that are less demanding of the land resource (World Bank, 2007).
